Johnson & Johnson and Amgen have criticised a meta-analysis which claims that the use of erythropoiesis-stimulating agents, such as Aranesp and Procrit increased the risk of blood clots and death among patients with cancer.

The analysis, which is published in the latest issue of the Journal of the American Medical Association, looked at 51 clinical trials involving 13,611 patients taking Amgen’s Epogen (epoetin alfa) and Aranesp (darbepoetin alfa) and Johnson & Johnson’s Procrit (also epoetin alfa). It showed patients being treated with the ESAs had about a 10% higher risk of dying than patients not receiving the drugs, which lead author Charles Bennett (a professor at Northwestern University) said was statistically significant.

The risk of venous thromboembolism was evaluated in 38 studies that included 8,172 patients and the studies found an increased blood-clot risk of 57% among patients receiving the anti-anaemia drugs. The authors of the meta-analysis claimed that the findings, “in conjunction with basic science reports on erythropoietin and erythropoietin receptors in solid cancers, raise concern about ESA safety for patients with cancer.”

The meta-analysis comes at a time when the US Food and Drug Adminstration and Medicare have expressed a considerable interest in the safety of ESAs. The FDA already ordered stronger warnings on the drugs’ labels last year, while Medicare restricted reimbursement of Epogen, Aranesp and Procrit when used to treat anaemia caused by chemotherapy, a decision Amgen is appealing.

Back to the analysis and Amgen is not impressed. Its executive vice president for R&D, Roger Perlmutter, said the study, provided little new information and the risks dealt with in the meta-analysis are already on the label. This view was echoed by J&J unit Ortho-Biotech.

Nothing that “all meta-analyses have limitations”, the firm said that the claims in JAMA “do not provide an accurate reflection of the safety profile” of ESAs. Ortho added that when
used according to product labelling, “ESAs remain safe and effective, and are the only proven treatment alternative to blood transfusions for patients with chemotherapy-induced anemia”.